US 20100058976 A1
The invention provides a display instrument, particularly for a motor vehicle, having an indicator that is rotatable about a rotational axis, wherein the indicator has an inner first region that is radial with regard to the rotational axis and that is not visible to a user, and an outer second region that is radial with regard to the rotational axis and that is visible to a user, wherein at a radial distance from the rotational axis an additional mounting of the indicator and/or a stop for receiving tilting moments positioned substantially perpendicular on the rotational axis are provided.
1. A display instrument, in particular for a motor vehicle, having a pointer which can rotate about a rotational axle, wherein the pointer has a first region which is radially on the inside with respect to the rotational axle and cannot be seen by a user, and a second region which is radially on the outside with respect to the rotational axle and can be seen by a user, characterized in that, at a radial distance from the rotational axle, an additional mount of the pointer and/or a stop are provided for taking up tilting moments which are essentially perpendicular to the rotational axle.
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The invention relates to an instrument for a motor vehicle, in which the greater part of a pointer which is mounted by means of a centrally arranged rotational axle is covered by an instrument component. In particular, the end of the pointer which is remote from the rotational axle encompasses the edges of the instrument component, as a result of which the tip of the pointer is visible. Such a pointer does not make use of the central zone of the visible region of an instrument, providing an unimpeded view of the instrument component, which can be embodied, for example, as a matrix display.
Such pointers, which cover a central zone of the visible region of an instrument, are known, for example, from documents WO 2006/005821 A1, JP 2003-014508, DE 197 39 628 or WO 2006/02474 A1. However, the protruding pointer design which this requires entails either a weight problem or a stability problem for the pointer. If a pointer is made very lightweight, it is susceptible to vibrations of the pointer tip. If the stability is improved, the loading on the rotational axle increases due to the long lever arm which acts on said rotational axle, and as a result the drive (engine or transmission) has to be made more robust and therefore becomes more expensive.
The invention has the object of making available a display instrument with improved resistance to shocks and vibrations.
The object is achieved by means of a display instrument, in particular for a motor vehicle, having a pointer which can rotate about a rotational axle, wherein the pointer has a first region which is radially on the inside with respect to the rotational axle and cannot be seen by a user, and a second region which is radially on the outside with respect to the rotational axle and can be seen by a user, wherein, at a radial distance from the rotational axle, an additional mount of the pointer and/or a stop are provided for taking up tilting moments which are essentially perpendicular to the rotational axle. According to a first embodiment, the additional mount is implemented by adding at least one further mount element to the mounting means for the rotational axle which are provided in the drive, while according to a second embodiment the additional mount is implemented by limiting the possible tilt angle of the pointer in relation to the spatial position of the unloaded rotational axle by surrounding the pointer shaft with a washer near to the drive block, which washer comes to bear on the counterpart which is attached to the drive block. This makes it possible overall both to equip the pointer in a comparatively lightweight fashion and therefore also to equip it with a moment of mass inertia which is small and can be easily rotated, as well as to ensure a comparatively stable arrangement of the pointer, in particular in surroundings in which vibrations of various types (strength and frequency) occur, as is the case in motor vehicles. According to the invention it is advantageously possible for an analog pointer which can rotate about a rotational axle to have very easy movement, a high degree of resistance to vibrations and also a high level of positioning accuracy with respect to adjacent components such as, for example, the dial located adjacent to or opposite the pointer tip.
In the first embodiment, in particular an additional holding angle piece is provided which is attached to or near to the drive housing, with the limb of the angle or of the holding angle piece which is parallel to the rotational axle being located in the circular sector over which the movement of the pointer does not pass. As a result it is possible for the pointer to be mounted or held at two different positions in the axial direction of the rotational axle of the pointer, with the two locations which are spaced apart in the axial direction of the rotational axle of the pointer being preferably located on the one side and the other side of the plane of movement or the cone of movement of the pointer. In a first subtype of this embodiment, a bearing bushing is provided in the angle piece in order to implement the additional mount, with the end of the drive shaft—which is also to be understood as a correspondingly constructed end piece of a pointer which is fitted (e.g. plugged) into a shaftless drive—which faces away from the drive side being mounted in the bearing bushing. This end piece can be embodied from the same material as the pointer material or can be formed from a material of higher strength. In a second subtype of this embodiment (which can be provided as an alternative or an addition to the first subtype), the holding angle piece is fitted with a ring which extends counter to the pointer and is configured with low sliding friction, at least at its potential contact surface with the pointer, specifically its end wall which is embodied as a flat contact track, this low friction being due to the selection of the ring material or to a coating, for example with nanoparticles or Teflon. On the opposite side of the pointer, an identical ring can be provided which is attached, for example, to the drive housing. As a result, a limiting stop, which counteracts swinging of the pointer through excitation of shocks or vibrations, is provided on both sides. This implements a stop for taking up tilting moments which are essentially perpendicular to the rotational axle. According to a further variant of a stop (which can be implemented alternatively or additionally to the other variants or embodiments) for taking up tilting moments which are essentially perpendicular to the rotational axle, a limiting stop or pair of limiting stops can also be arranged further away from the rotational axle, depending on the available installation space or the inherent resonant behavior of the pointer. A holding angle piece is not absolutely necessary for this.
In the second embodiment it is advantageous if the contact surface, which is punctual, sectoral or runs around in a circular path depending on the load case, is effective at a considerable distance from the rotational axle so that the opposing force counteracting the tendency to tilt remains as small as possible owing to the lever laws; this is because the frictional losses occurring as a result of the contact surface increase proportionally to the force with which the pointer washer and its counterpart are pressed one on top of the other. In one configuration of the invention according to the second embodiment, the tilt angle is restricted to a value of precisely or virtually zero degrees due to permanent contact between the washer and the counterbearing. A lubricant can be introduced in the region of the contact surface or a friction-reducing coating may be provided, for example a PTFE (polytetrafluoroethylene, Teflon) coating or the like. As an alternative to this, rolling bodies may be introduced in the region of the contact surface, which rolling bodies are held on the circular path by a depression, formed as a circular channel, in the washer or the counterbearing.
The measures presented in the various embodiments can also be combined with one another.
According to the invention it is preferred, in particular, if the pointer bears in a continuously sliding fashion on the additional mount and/or on the stop. As a result, comparatively simple means can be used to implement a comparatively stable mount which also has a high degree of resistance to shocks. It is particularly preferred here if the pointer is mounted in an easily moving fashion or bears in an easily moving fashion on the additional mount and/or on the stop by means of a lubricant or a friction-reducing coating, in particular a PTFE layer (Teflon layer). As a result, the frictional forces which for a movement of the pointer about the rotational axle owing to the continuous additional mounting or owing to the merely temporary bearing on the stop, can be reduced to a considerable degree and with comparatively little effort.
According to the invention, it is also particularly preferred if the pointer bears in a continuous fashion on the additional mount and/or on the stop by means of a rolling body. As a result, frictional force for moving the pointer about the rotational axle can be reduced to an even greater degree. However, the mount can also be embodied in such a way that contact occurs between the guide region of the pointer and the limiting element only if shocks occur.
It is particularly preferred if a rotational axle bearing which is remote from the drive block is provided as the additional mount or if a washer and a counterpart are provided as the additional mount. As a result it is possible to implement the additional mount with structurally simple means.
Furthermore it is preferred according to the invention that first limiting stops and/or second limiting stops are provided as the stop. As a result it is particularly advantageously possible for the pointer to be rotated both in a particularly easily moving fashion about the rotational axle in the normal operating mode, i.e. when the vibration loading is not excessively large, and for effective and continuously acting protection against excessive vibration loading or shock loading to be implemented with very simple means.
According to the invention it is particularly advantageous if the pointer is embodied, for example, as a hook-type pointer. As a result a wide variety of types and forms of pointer can be implemented in the display instrument according to the invention.
According to the refinements of the first embodiment of the attachment of the pointer 3 in the display instrument 10 according to the invention which are illustrated in
The arrangement of a washer 1′ which encompasses the shaft of the pointer and has a counterpart 2′ which interacts with it is shown in